FIG. 1 depicts a known solution exploiting the Talbot effect for generating an array of light spots.
The array of light spots 101 is generated by an array of apertures 102 which exploits the Talbot effect. The Talbot effect is a diffraction phenomenon working as follows. When a coherent light beams, such as the input light beam 103, is applied to an object having a periodic diffractive structure (thus forming light emitters), such as the array of apertures 102, the diffracted light recombines into identical images of the emitters at a plane located at a predictable distance zt from the diffracting structure. This distance zt is known as the Talbot distance. The Talbot distance zt is given by the relation zt=2.n0.p2/λ, where p is the periodic spacing of the light emitters, λ is the wavelength of the input light beam, and n0 is the refractive index of the propagation space.
More generally, re-imaging takes place at other distances zm spaced further from the emitters and which are a multiple of the Talbot distance z such that zm=2.n0.m.p2/λ, where m is an integer.
This known solution however has technical limitations since the intensity of the light spots cannot be high because just a few percents of the input light beam wave plane passes through the apertures.